Prior Art
The prior art shows several variations on the theme of self-shielding or automatic shielding hypodermic syringes. These patents generally can be spoken of as directed to providing a cover or shield which prevents someone from sticking themselves with the needle.
These needle covers generally describe similar elements. A syringe, a needle (with a means for attaching the needle to the syringe), and a mechanism for providing a temporary cover for the needle. In these particulars, the present invention is similar to the prior art.
The invention differs from the prior art at the point where the needle cap, that part of the needle assembly which protects the needle when it is shipped from a manufacturer, interacts with the needle cover which covers the exposed needle on the syringe.
In reviewing the what is believed to be the closest prior art, U.S. Pat. No. 4,911,693 (Paris) discloses a hypodermic syringe needle guard with a first cylindrically shaped part surrounds and is fixed to the needle base which is mounted on the forward end of the syringe body. A second cylindrical part is mounted within the first part for axial movement between a forward position where the needle is surrounded for protection of the needle prior to mounting and between injections and a position in which the needle is exposed during an injection. A spring urges the second part towards the forward position. Locking elements are provided for permanently locking the second part in a third, axially spaced position to protect the needle after it has been discarded. Prior to and between injections, the second part may be non-permanently locked in the forward position by rotating it relative to the first part.
U.S. Pat. No. 5,137,521 (Wilkins) discloses a safety shield slidable mounted upon a disposable hypodermic syringe and needle assembly and having an elongated guide slot which cooperates with a resilient tab cooperating therewith to maintain orientation between the syringe body and the telescoping shield. A resilient locking tab integral with the syringe body cooperates with a pair of spaced slots arranged along the telescoping shield to define the initial shielded position and the usable position respectively. The telescoping shield to define the initial shielded position ad the usable position respectively. The telescoping shield includes a shoulder which receives the bent-over flexible tab to lock the shield in the shielded position to prevent contact with the needle, facilitating safe handling of the assembly.
U.S. Pat. No. 5,318,547 (Altschuler) discloses a sheathed syringe assembly including a syringe having a cylindrical body provided with a needle at one thereof and a plunger slidable disposed within said cylindrical body for aspirating or dispensing substances into or from the cylindrical body. A sheath assembly comprised of inner and outer tubular members is attached to the cylindrical body. The inner tubular member is telescopically received in the outer member for reciprocal movement therein between a retracted position exposing said needle and an extended position covering said needle to prevent accidental needle stick.
U.S. Pat. No. 4,892,521 (Laico, et al.) discloses a protective cover for a hypodermic needle which employs a pair of guide rods for guiding a protective cap from a retracted position to an extended protective position for shielding the hypodermic needle. A guide member projects transversely from the needle base and forms a pair of apertures which receive and interact with the guide rods. The guide rods are fixed to a protective cap portion of the cover. A guide rod mechanism is also employed in connection with a retractable, foldable sheath embodiment. The protective cover assembly may also take form of telescopic shield sections which lock in the extended protective position by means of a cooperative projection/groove locking engagement.
U.S. Pat. No. 5,222,945 (Basnight) discloses a safety syringe which includes a barrel having an interior chamber for containing fluid, and a needle mounted at one end of the barrel. The needle has a bore in fluid communication with the interior chamber in the barrel. A plunger is slidable mounted within the interior chamber of the barrel for displacing fluid within the barrel through the needle to administer fluid to a patient. A protective shield is slidable mounted on the barrel and is moveable between an extended position in which the needle is concealed and a retracted position in which the needle is exposed. The protective shield is moveable between first, second and third position. In the first position, the protective shield is extended over the needle and is releasibly locked to protect the needle prior to use. In the second position, the protective shield is retracted and is releasibly locked to facilitate use of the syringe. In the third position, the protective shield is again extended to cover the needle and is irreversibly locked to prevent reuse of the syringe. Reuse of the syringe is further prevented by a plunger locking mechanism which is engaged when the plunger is fully depressed.